THIS invention relates to apparatus for circulating a fluid from a first end to a second end of the apparatus, for example for filtration of the fluid, for separation of solids by gravity separation, for mixing, for mineral flotation separation and the like, and to methods of use of the apparatus.
It is well known to form support structures such as roadways, canals or river or bank linings and the like from a material having a honeycomb structure, i.e., having a plurality of compartments or cells divided by dividing walls, each compartment or cell being filled with a suitable filler material. However, there is always a need for new methods of utilising this tube material.
According to the invention there is provided apparatus for circulating a fluid, i.e a liquid or a gas, from a first end to a second end, the apparatus comprising:
(1) a tube of a flexible material divided by dividing walls of a flexible material into an array of compartments or cells running the length of the tube, the compartments being arranged in rows and columns so that the tube divided by dividing walls has a honeycomb structure, with a first end of the tube on a base and a second end of the tube above the first end of the tube;
(2) first flow means at or near the first end of the tube, and either in the dividing walls between the first and second rows and between the third and fourth rows and between each succeeding pairs of rows, or in the dividing walls between the second and third rows and between the fourth and fifth rows and between each succeeding pairs of rows;
(3) second flow means at or near the second end of the tube, and either in the dividing walls between the second and third rows and between the fourth and fifth rows and between each succeeding pairs of rows, or in the dividing walls between the first and second rows and between the third and fourth rows and between each succeeding pairs of rows, so that the first flow means and the second flow means alternate;
(4) support means for supporting the tube in position on the base;
(5) a fluid inlet into the first row of compartments; and
(6) a fluid outlet from the last row of compartments;
so that fluid introduced through the fluid inlet flows either up or down the compartments in the first row, through the first or second flow means between the first and second rows, and then down or up the compartments in the second row, through the second or first flow means between the second and third rows, and so on until the fluid reaches the fluid outlet.
Clearly, when the first flow means are located in the dividing walls between the first and second rows and between the third and fourth rows and between each succeeding pairs of rows, then the second flow means are located in the dividing walls between the second and third rows and between the fourth and fifth rows and between each succeeding pairs of rows, and when the first flow means are located in the dividing walls between the second and third rows and between the fourth and fifth rows and between each succeeding pairs of rows, then the second flow means are located in the dividing walls between the first and second rows and between the third and fourth rows and between each succeeding pairs of rows. In other words, the first flow means and the second flow means alternate.
In a first embodiment of the invention, the first flow means may be provided by spacing the dividing walls between a pair of rows from the base (with the dividing walls of adjacent rows touching the base), and the second flow means may be provided by extending the dividing walls between a pair of rows above the dividing walls of adjacent rows. Thus, in this embodiment of the invention, a dividing wall between a first and a second row is spaced from the base and extends above the dividing walls of adjacent rows, the dividing wall between a second and a third row of compartments touches the base and is lower than the dividing walls of adjacent rows, the dividing wall between a third and a fourth row of compartments is spaced from the base and extends above the dividing walls of adjacent rows, and so on.
In a second embodiment of the invention, each first flow means comprises an aperture in a dividing wall between a pair of rows and likewise each second flow means comprises an aperture in a dividing wall between a pair of rows. Generally, such apertures will be provided in each of the compartments in each of the rows. Thus, in this embodiment, a series of apertures are located at or near the first end of the tube in a first row of compartments, a series of apertures are located at or near the second end of the tube in a second row of compartments adjacent the first row, a series of apertures are located at or near the first end of the tube in a third row of compartments adjacent the second row, a series of apertures are located at or near the second end of the tube in a fourth row of compartments adjacent the third row, and so on.
The support means for supporting the tube in position on the base may be for example a container defined by one or more side walls and the base, into which the tube is located and secured. The tube may be secured in the container in any suitable manner, for example by attaching the corners of the tube to the corners of the container.
Alternatively, the support means may comprise a series of flexible strings or rigid stays located through suitable rows and columns of compartments, generally at or near the edges of the tube, which flexible strings or rigid stays are attached to fixed objects to support the tube with the first end of the tube on the base and the second end of the tube above the first end.
Thus, for example, when the tube is substantially rectangular in plan view, a string or a stay may be located in at least a row or a column of compartments at or near each of the four edges of the tube.
The use of flexible strings or rigid stays to support a tube in position is described in more detail in co-pending application PCT/IB99/00965.
Further alternatively the outer walls of the tube may be made sufficiently rigid so that the tube is self supporting.
The cross-sectional size of the compartments may reduce or increase in size from the compartments of the first row of compartments to the compartments of the last row of compartments. For example, the compartments may be of three different sizes, with the cross-sectional size of the compartments in the first row and in one or more rows adjacent the first row being greater than the cross-sectional size of the compartments of one or more rows intermediate the first and last rows of compartments, which in turn have a greater cross-sectional size than the cross-sectional size of the compartments in the last row and in one or more rows adjacent the last row of compartments.
The use of compartments with different cross-sectional sizes is described in more detail in co-pending application PCT/IB99/00967.
One or more of the compartments may include a baffle or baffles to direct the flow of the fluid through the compartment concerned. For example, where the flow of fluid enters a compartment at a leading wall of that compartment, the leading wall may have attached thereto one or more baffles to direct the flow of fluid onto the opposite wall or walls of the compartment. As another example, all of the walls of the compartment may have attached thereto one or more baffles so as to create a mixing of the fluid flowing through the compartment in that compartment.
The baffle or baffles may be attached to the walls of the compartments or may form an insert to be inserted into the compartments.
The base of the apparatus may be located above a space, the space having an outlet, the base being adapted to being moved to allow any material in the compartments of the tube to move into the space from where the material may be removed via the outlet. This provides for easy cleaning of the apparatus of the invention.
The base of the apparatus may also comprise or include, in each compartment, a funnel shaped insert, which may either be attached to the compartment or be an insert in the compartment, each funnel shaped insert having a central hole through which material may be removed or through which a fluid may be forced into the compartment concerned.
The tube may also be adapted to be lifted off the base to allow for removal of material on the base.
The tube and the dividing walls may be made from any suitable flexible material. Although the material must possess some degree of flexibility, the degree of flexibility may range from very flexible up to semi-rigid. The flexible material may be for example a plastics material such as for example a co-extruded or a bi-axially extruded plastics material; a plastics mesh material; a plastics laminate material such as for example a laminate of a plastics material and a metallic material or a textile material; a metallic material; a woven or non-woven textile material; a paper or cardboard material; and the like.
The flexible material is preferably a suitable plastics material.
The tube may have any suitable height and any suitable compartment size. For example, the height of the tube may range from 100 mm to 10 m and each compartment may have a wall length of from 5 mm up to 2 m.
The tube may be shaped, e.g by cutting the compartments in one or more rows or columns at an angle, to fit into a desired space, e.g the interior of a tank or the like or to allow overflow from the apparatus when it is used as a trickle bed filter.
The compartments in the tube may have any suitable cross-section, such as triangular, square, hexagonal or octagonal, but preferably have a square cross-section, i.e each compartment is defined by four walls of substantially equal length.
One or more of the compartments may be filled with a suitable filler material such as for example ceramic Raschig rings, marbles, glass beads, sand, copper or stainless scrubbing pads and the like. Such fillers may be selected according to the intended use of the apparatus of the invention.
The fluid inlet into the first row of compartments may be located in any suitable position in the compartments, generally at or near the second end of the tube or at or near the first end of the tube. Likewise the fluid outlet from the last row of compartments may be located in any suitable position in the compartments, generally at or near the first end of the tube, or at or near the second end of the tube.
The apparatus may include one or more additional inlets into specific compartments or into specific rows or columns of compartments, for the introduction of a gas, liquid or solid, or to allow heat exchange to take place, while the fluid is circulating through the apparatus.
The apparatus of the invention has many uses.
The apparatus of the invention may be used for the treatment of a liquid containing suspended solids to remove the solids therefrom and/or to separate the solids into fractions according to their densities. In this case the solids settle at the bottoms of the containers on the base, while the liquid moves forward and ultimately out of the fluid outlet. This treatment may be sewage treatment, water treatment, mines slimes treatment, brewing waste treatment, animal manure treatment or the like.
In the case of water purification treatment, the compartments in one or more of the rows, particularly the rows at or close to the last row of compartments, may include a filtration medium such as charcoal or diatomaceous earth or the like, or a filtration insert such as plastic net rolled into a roll to increase the surface area available in the compartments, or may include a material which changes the composition of the water, e.g limestone, or steel wool, to assist in the water treatment.
This system of water treatment may also be used to separate oil from water, for example to remove an oil slick from the sea.
The apparatus of the invention may also be used for the chemical mixing of a particular liquid or gas or solid chemical or chemicals into a bulk liquid. In this case, the bulk liquid is circulated from the fluid inlet through the apparatus, with the liquid or gas or solid chemical or chemicals being introduced into compartments in one or more of the rows, with the final mixture being removed through the fluid outlet. The apparatus of the invention provides for good mixing of the various components, particularly when the compartments include suitable baffles to promote mixing.
The apparatus of the invention may also be used as a methane digester.
The apparatus of the invention may also be used in agriculture and as a fish hatchery, with fish spawn or small fish being kept in the compartments with a constant flow of running water over them, the water containing the nutrients necessary for growth. Every alternate row of compartments may be filled with a suitable feed material, with the fish spawn or small fish having access to the feed material through small apertures in the walls defining the compartments, so as to protect the feed material from pollution.
The production of full grown aquaculture life may be increased by the high flow rate of the apparatus of the invention, the introduction of oxygen at certain stages, and the removal of waste products without affecting the flow of the water and life of the tank. The apparatus also allows for the removal of the live product in stages without interfering with the adjacent compartments.
The apparatus of the invention may also be used in many other applications such as for example swimming pool filters; the cleaning of polluted rivers; in chemical process plants; in froth flotation mineral separation; to remove ash from smoke stack effluent with the removal of sulphur and other chemicals; in bio-leaching using bacteria to remove minerals from ore bodies; in chemical leaching of minerals from ore bodies; in an irrigation system to remove seeds and sand from irrigation water and to mix in fertilizers and chemicals into the irrigation water in one apparatus; and the like.